1. Field of the Invention
This invention relates to a rotary valve mechanism for improving the fuel efficiency of automobile and other throttled, spark ignition internal combustion engines of both the two stroke cycle and four stroke cycle types, by minimizing the pumping losses or negative work even below the corresponding loss levels in compression ignition or diesel engines.
2. Description of the Prior Art
Throttled spark-ignition internal combustion engine technology is well known in the art. For a detailed description of the prior art, reference should be made to the file wrapper of the above identified co-pending disclosure.
In an automobile engine of the internal combustion type, the carburetor throttle is adjusted by the driver, through manipulation of the accelerator pedal, to a position which gives the desired power output. This throttling drops the engine intake pressure below atmospheric level thereby decreasing the engine performance to the required value. After the combustion process is completed in the various cylinders of the engine, the exhaust must be pumped out of such cylinders against atmospheric pressure. This in turn of course requires work to be expended to accomplish the flow of such exhaust against the existing atmospheric pressure on the exterior of the combustion cylinders. The pressure energy lost by the carburetor restriction must be replaced by work which would otherwise be available as useful power output at the flywheel if such energy were not required in exhausting the combustion cylinders. The above problems of course do not apply to diesel type engines which have no air throttle and therefore do not have this flow-work loss to reduce their efficiency.
However, such diesel type engines are inherently much more expensive and have reduced specific performance characteristics compared to conventional spark ignition internal combustion engines. Such engines must compress the air charge to high pressures and to ignition temperature whether at full load or at idling conditions.
Accordingly, there is a need for a device useful in gasoline engine applications that would substantially eliminate the negative work required of such engines due to throttled fuel intake of such engines. A practical device to eliminate such negative work does not appear in the prior art.